title: Meprin A impairs epithelial barrier function, enhances monocyte migration, and cleaves the tight junction protein occludin.
abstract: Meprin metalloproteases are highly expressed at the luminal interface of the intestine and kidney and in certain leukocytes. Meprins cleave a variety of substrates in vitro, including extracellular matrix proteins, adherens junction proteins, and cytokines, and have been implicated in a number of inflammatory diseases. The linkage between results in vitro and pathogenesis, however, has not been elucidated. The present study aimed to determine whether meprins are determinative factors in disrupting the barrier function of the epithelium. Active meprin A or meprin B applied to Madin-Darby canine kidney (MDCK) cell monolayers increased permeability to fluorescein isothiocyanate-dextran and disrupted immunostaining of the tight junction protein occludin but not claudin-4. Meprin A, but not meprin B, cleaved occludin in MDCK monolayers. Experiments with recombinant occludin demonstrated that meprin A cleaves the protein between Gly(100) and Ser(101) on the first extracellular loop. In vivo experiments demonstrated that meprin A infused into the mouse bladder increased the epithelium permeability to sodium fluorescein. Furthermore, monocytes from meprin knockout mice on a C57BL/6 background were less able to migrate through an MDCK monolayer than monocytes from their wild-type counterparts. These results demonstrate the capability of meprin A to disrupt epithelial barriers and implicate occludin as one of the important targets of meprin A that may modulate inflammation.
authors.affiliation: Dept. of Biochemistry and Molecular Biology, The Pennsylvania State Univ. College of Medicine, 500 University Dr., H171, Hershey, PA 17033, USA.
authors.forename: Jialing
authors.initials: J
authors.lastname: Bao
authors.forename: Renee E
authors.initials: RE
authors.lastname: Yura
authors.forename: Gail L
authors.initials: GL
authors.lastname: Matters
authors.forename: S Gaylen
authors.initials: SG
authors.lastname: Bradley
authors.forename: Pan
authors.initials: P
authors.lastname: Shi
authors.forename: Fang
authors.initials: F
authors.lastname: Tian
authors.forename: Judith S
authors.initials: JS
authors.lastname: Bond
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000187:drug effects; D004285:Dogs; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D061985:Madin Darby Canine Kidney Cells; D008666:Metalloendopeptidases / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009000:Monocytes / Q000502:physiology*; D062793:Occludin / Q000378:metabolism*; D010539:Permeability / Q000187:drug effects; D019108:Tight Junctions / Q000378:metabolism
chemical_list: D062793:Occludin; D008666:Metalloendopeptidases; C053833:meprin A; C095663:meprin B
keywords: Madin-Darby canine kidney cells; knockout mice; metalloproteinase; tight junction proteins